The synthesis of novel hypervalent nonmetal species and studies of the chemical properties of these new types of organo-nonmetallic species is the primary goal of this research. Newly developed methods for the synthesis of ligands designed to strongly stabilize the bonding in these hypervalent species have been perfected. This males possible the formation of a wide variety of unprecedented types of compounds of main group elements on a large scale with rapid synthesis. These novel compounds have usually been requested for NCI anticancer drug screening, so the more rapid synthetic methodology will make more such species available in a much shorter time period than formation of our research products has required in previous years. The large scale synthetic methodology has made accessible a new compound which will be used to introduce 18F substituents into estrogens. This is expected to be later used in positron emission tomography for the imaging of human breast tumors. Methods recently developed for the synthesis of unique monodentate, bidentate, tridentate and tetradentate ligands for hypervalent nonmetal species will be used for the synthesis of a wide variety of main group element species. Many of these, which were already synthesized in our group, have important applications in synthetic organic chemistry (e.g., the commercially available Dess-Martin Periodinane and the Martin Sulfurane). An improved synthetic method for the Periodinane will be sought, since the starting material for orr current synthetic method has recently been found to be explosive under some conditions. The tetradentate ligand is a cis cyclobutanetetraol which makes square pyramidal four coordinate hypervalent species which are polymerizable, giving species to be studied in the solid state. Chiral hydride- substituted hypervalent species will be studied as possible reagents for the production of optically active reduced species by chirality transfer. A monodentate ligand to be studied is produced by attachment of a singlet electrophilic carbene to the nonmetal. It has been used to form the first chloronium ylide stable enough to provide an X-ray crystallographic structure.